U.S. patent number 10,199,323 [Application Number 15/415,496] was granted by the patent office on 2019-02-05 for flexible circuit substrate with temporary supports and equalized lateral expansion.
This patent grant is currently assigned to Apple Inc.. The grantee listed for this patent is Apple Inc.. Invention is credited to Sinan Alousi, Paul S. Drzaic, Yung-Yu Hsu, Hoon Sik Kim, David M. Kindlon, Christopher A. Schultz, Terry C. Shyu, Daniel D. Sunshine.
United States Patent |
10,199,323 |
Hsu , et al. |
February 5, 2019 |
Flexible circuit substrate with temporary supports and equalized
lateral expansion
Abstract
An item may have a flexible support structure and may include a
flexible component. The flexible component may have electrical
components mounted on component mounting regions in a flexible
circuit substrate. The component mounting regions may be
interconnected by serpentine interconnect paths or other flexible
interconnect paths. The flexible circuit substrate and component
mounting regions may extend along a longitudinal axis of the
flexible component or may form a two-dimensional array.
Two-dimensional mesh-shaped flexible circuit substrates may be used
in forming displays. The mesh-shaped flexible circuit substrates
may be auxetic substrates that widen when stretched (e.g.,
structures with a negative Poisson's ratio that become thicker
perpendicular to applied force when stretched) and that therefore
reduce image distortion. Temporary tethers may help hold flexible
circuit substrates together until intentionally broken following
assembly of a flexible component into the flexible support
structure.
Inventors: |
Hsu; Yung-Yu (San Jose, CA),
Kim; Hoon Sik (San Jose, CA), Schultz; Christopher A.
(San Francisco, CA), Kindlon; David M. (Lake Arrowhead,
CA), Sunshine; Daniel D. (Sunnyvale, CA), Drzaic; Paul
S. (Morgan Hill, CA), Alousi; Sinan (Campbell, CA),
Shyu; Terry C. (Mountain View, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
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Assignee: |
Apple Inc. (Cupertino,
CA)
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Family
ID: |
61243437 |
Appl.
No.: |
15/415,496 |
Filed: |
January 25, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180061743 A1 |
Mar 1, 2018 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62381382 |
Aug 30, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K
1/148 (20130101); H01L 23/49838 (20130101); H05K
1/0283 (20130101); H01L 33/62 (20130101); H01L
25/0753 (20130101); H01L 23/4985 (20130101); H05K
1/189 (20130101); H05K 2203/302 (20130101); H05K
2201/0909 (20130101); H05K 2201/09127 (20130101); G06F
3/041 (20130101); H05K 2201/09063 (20130101); H05K
2201/09263 (20130101); H05K 2201/10106 (20130101); H05K
2201/053 (20130101) |
Current International
Class: |
H01L
23/498 (20060101); H05K 1/02 (20060101); H01L
25/075 (20060101); H01L 33/62 (20100101); H05K
1/14 (20060101); G06F 3/041 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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205048218 |
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Feb 2016 |
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CN |
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2016030578 |
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Mar 2016 |
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WO |
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2016100218 |
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Jun 2016 |
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WO |
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2016198312 |
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Dec 2016 |
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WO |
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Other References
Mark et al., "Auxetic Metamaterial Simplifies Soft Robot Design",
International Conference on Robotics and Automation, May 16-21,
2016, 4951-4956, Sweden. cited by applicant.
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Primary Examiner: Landau; Matthew C
Assistant Examiner: Hatzilambrou; Mark
Attorney, Agent or Firm: Treyz Law Group, P.C. Treyz; G.
Victor Cole; David K.
Parent Case Text
This application claims the benefit of provisional patent
application No. 62/381,382, filed Aug. 30, 2016, which is hereby
incorporated by reference herein in its entirety.
Claims
What is claimed is:
1. A flexible component, comprising: a flexible circuit substrate
having a plurality of component mounting regions interconnected by
flexible interconnect paths; temporary tethers that are configured
to temporarily couple the component mounting regions together and
strengthen the flexible circuit substrate when the temporary
tethers are in an unbroken state, wherein the temporary tethers are
broken during assembly of the flexible component into an item,
wherein the temporary tethers are configured to remain in a broken
state within the item, and wherein the temporary tethers are
interspersed between the flexible interconnect paths; metal lines
in the flexible circuit substrate; and electrical components that
are mounted to the component mounting regions and that are
interconnected by the metal lines.
2. The flexible component defined in claim 1 wherein each of the
temporary tethers has a narrowed region that facilitates breaking
of the temporary tethers.
3. The flexible component defined in claim 2 wherein the electrical
components each include at least one light-emitting diode.
4. The flexible component defined in claim 3 wherein the flexible
circuit substrate comprises a polyimide layer, wherein the flexible
interconnect paths comprise serpentine portions of the polyimide
layer that extend from the component mounting regions, and wherein
the temporary tethers are formed from integral portions of the
polyimide layer.
5. The flexible component defined in claim 1 wherein the flexible
circuit substrate is an elongated flexible circuit substrate having
a longitudinal axis, wherein the component mounting regions extend
along the longitudinal axis, wherein the component mounting regions
include adjacent pairs of component mounting regions, wherein each
pair of adjacent component mounting regions is coupled by a
respective set of the temporary tethers, and wherein each set of
temporary tethers includes at least first and second tethers of
different strengths.
6. An item, comprising: a flexible support structure; an auxetic
mesh-shaped flexible circuit substrate having a two-dimensional
array of component mounting regions coupled by interconnect paths,
wherein the flexible circuit substrate comprises a polymer, wherein
portions of the flexible circuit substrate form temporary tethers,
wherein the temporary tethers are configured to temporarily couple
the component mounting regions together and strengthen the flexible
circuit substrate when the temporary tethers are in an unbroken
state, wherein the temporary tethers are broken during assembly of
the item, and wherein the temporary tethers are configured to
remain in a broken state within the item; and an array of
electrical components, wherein each electrical component is mounted
to a respective one of the component mounting regions and is
interconnected to at least one other of the electrical components
with metal traces in the auxetic mesh-shaped flexible circuit
substrate and wherein each electrical component comprises at least
one light-emitting diode.
7. The item defined in claim 6 wherein the auxetic mesh-shaped
flexible circuit substrate comprises polyimide and wherein each
electrical component includes at least one crystalline
semiconductor die.
8. The item defined in claim 7 wherein each crystalline
semiconductor die comprises the at least one light-emitting
diode.
9. The item defined in claim 6 wherein the flexible support
structure comprises fabric.
10. The item defined in claim 6 wherein each temporary tether has a
portion coupled to one of the interconnect paths.
11. The item defined in claim 6 wherein each electrical component
comprises a communications circuit and at least three
light-emitting diodes.
12. The item defined in claim 11 wherein each of the light-emitting
diodes has a different color and is formed from a respective
crystalline semiconductor die.
13. The item defined in claim 12 wherein the support structure
comprises strands of material and is configured to stretch.
14. The item defined in claim 6 wherein the electrical components
include sensors.
15. The item defined in claim 6 further comprising a non-auxetic
flexible circuit substrate structure coupled to the auxetic
flexible circuit substrate.
Description
BACKGROUND
This relates generally to components formed from flexible circuit
substrates, and, more particularly, to items formed from components
with flexible circuit substrates having regions interconnected by
elongated interconnect paths.
Electrical components such as integrated circuits can be mounted on
dielectric substrates. Signals may be routed between electrical
components using metal traces on a dielectric substrate. Some
substrates such as rigid printed circuit boards are inflexible.
Other substrates such as flexible printed circuit substrates may
bend, thereby allowing these substrates to be used in applications
were the inflexible nature of rigid printed circuit boards would
not be acceptable.
It can be challenging to form flexible circuit substrates with
desired attributes. If care is not taken, a flexible circuit
substrate may be insufficiently flexible or may be insufficiently
robust. Flexible circuit substrates may also distort undesirably
when stressed.
SUMMARY
An item may have a flexible support structure. The flexible support
structure may be formed from a stretchable material such as fabric,
elastomeric polymer, or other stretchable structures. The item may
include a flexible component that is supported by the flexible
support structure. For example, the item may have a flexible
component that is embedded within a fabric structure or that is
attached to an elastomeric plastic support. The flexible component
may have a flexible circuit substrate. The flexible component may
also have electrical components mounted on component mounting
regions in the flexible circuit substrate. The component mounting
regions may be interconnected by serpentine interconnect paths or
other flexible interconnect paths in the flexible circuit
substrate.
The flexible circuit substrate may have an elongated shape that
extends along a longitudinal flexible component axis or may have a
two-dimensional shape. The electrical components mounted on the
component mounting regions of the flexible circuit substrate may
include touch sensors and other sensors, light-based components
such as light-emitting diodes, communications and control circuit,
and other circuitry. Two-dimensional mesh-shaped flexible circuit
substrates may be used in forming displays. The mesh-shaped
flexible circuit substrates may be auxetic substrates that widen
when stretched (e.g., structures with a negative Poisson's ratio
that become thicker perpendicular to applied force when stretched).
A flexible component such as a flexible display that uses an
auxetic substrate may exhibit reduced image distortion.
Temporary tethers may help hold flexible circuit substrates
together until intentionally broken following assembly of a
flexible component and flexible support structure to form an item.
The temporary tethers may be formed from integral portions of a
flexible circuit substrate or separate structures and may have
selectively narrowed portions to facilitate splitting the tethers
in known locations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of an illustrative item of the type that may
include circuitry mounted on a flexible circuit substrate in
accordance with an embodiment.
FIG. 2 is a perspective view of circuitry on a flexible circuit
substrate having component mounting regions interconnected by
stretchable elongated serpentine interconnect paths in accordance
with an embodiment.
FIG. 3 is a top view of a pair of component mounting regions, an
interposed serpentine interconnect path, and temporary support
structures in accordance with an embodiment.
FIGS. 4, 5, 6, 7, 8, 9, 10, and 11 are illustrative temporary
support structures in accordance with embodiments.
FIG. 12 is a diagram of an illustrative pair of component mounting
regions formed from flexible circuit substrate material that have
been coupled by temporary support structures that are separate from
the flexible circuit substrate material in accordance with an
embodiment.
FIG. 13 is a diagram of an illustrative pair of component mounting
regions formed from flexible circuit substrate material that have
been coupled by temporary support structures that extend outwardly
from the component mounting regions in accordance with an
embodiment.
FIG. 14 is a perspective view of an illustrative stretchable item
showing how the item may be formed from a flexible circuit
substrate material that expands laterally in a direction that is
perpendicular to a stretching direction in accordance with an
embodiment.
FIG. 15 is a diagram of an illustrative auxetic mesh flexible
circuit substrate in an unstretched configuration in accordance
with an embodiment.
FIG. 16 is a diagram of the auxetic mesh flexible circuit substrate
of FIG. 15 when stretched in accordance with an embodiment.
FIGS. 17, 18, and 19 are diagrams of additional illustrative
patterns that may be used for forming auxetic mesh flexible printed
circuit substrates in accordance with embodiments.
DETAILED DESCRIPTION
An illustrative item that may include a component formed from a
flexible circuit substrate is shown in FIG. 1. As shown in FIG. 1,
item 10 may be formed from support structure 12. Support structure
12 may include one or more layers of fabric or other material that
includes strands of material such as strands 14 (e.g., insulating
and/or conductive yarn), may be formed from sheets of plastic,
molded or machined plastic structures, metal structures, structures
formed from fiber-composite material, and/or structures formed from
other materials. Structure 12 may form a wearable item (e.g., a
band to be worn on a user's wrist), may form an electronic device
housing (e.g., a housing for a cellular telephone, laptop computer,
tablet computer, or other electronic device), may form a case or
cover for an electronic device, and/or may form other suitable
items. If desired, item 10 may be flexible. For example, structure
12 may be flexed in directions 20 about bend axis 18. Structures 12
may also be deformed in other directions (e.g., by stretching).
One or more components such as illustrative component 16 may be
supported by support structure 12. For example, component 16 may be
embedded within structure 12 (e.g., component 16 may be received
within a pocket between adjacent fabric layers, may be mounted in a
recess in a plastic or metal structure, may be attached to an
interior and/or exterior portion of structure 12 using adhesive, or
may otherwise be incorporated into structure 12). To accommodate
deformation of structure 12, component 16 may be formed from a
flexible circuit substrate.
An illustrative flexible electronic component formed from a
flexible circuit substrate is shown in FIG. 2. As shown in the
perspective view of FIG. 2, flexible electronic component 16 may be
formed from flexible circuit substrate 22. Flexible circuit
substrate 22 may be formed from a flexible dielectric material such
as polyimide or other flexible polymer that allows component 16 to
flex. Component 16 may, for example, stretch longitudinally outward
in directions 30 (e.g., along a longitudinal axis associated with
an elongated component such as illustrative component 16 of FIG. 2)
and/or may bend about bend axis 18.
Electrical components 24 may include packaged and/or unpackaged
integrated circuits or other semiconductor dies. Unpackaged
circuits may be formed from bare silicon dies or other crystalline
semiconductor dies. Packaged integrated circuits may be
encapsulated within plastic packages. If desired, packaged circuits
and/or unpackaged circuits may be mounted on interposer structures.
Integrated circuit packages, interposers, and other structures for
packaging and mounting circuitry associated with electrical
components 24 may be formed from plastic, ceramic, and/or other
dielectric materials.
Electrical components 24 may include devices for gathering input
and/or supplying output. With one illustrative configuration,
components 24 may include light-emitting diodes such as
light-emitting diodes 26 and associated control and communications
circuitry such as circuitry 28. Light-emitting diodes 26 may be
formed from organic light-emitting diode structures or may be
formed from crystalline semiconductor dies (e.g., light-emitting
diodes 26 may be micro-LEDs). There may be any suitable number of
light-emitting diodes 26 in each components 24 (e.g., one or more,
two or more, three or more, etc.). The light-emitting diodes in
each component 24 may be light-emitting diodes 26 of different
colors such as red, green, and blue light-emitting diodes. In
general, components 24 may be any suitable electrical components
(e.g., integrated circuits, discrete components, light-emitting
components, light sensors, touch sensor components such as
capacitive touch sensor components, light-emitting and
light-detecting touch sensor components, force sensors, temperature
sensors, pressure sensors, moisture sensors, other sensors, haptic
output devices, audio components, etc.). Illustrative
configurations in which components 24 include at least some
light-emitting components such as light-emitting diodes 26 and that
optionally include touch sensor components may sometimes be
described herein as an example. This is, however, merely
illustrative. Components 24 may be any suitable electrical
components mounted to flexible circuit substrate 22.
Flexible circuit substrate 22 may have component mounting regions
such as component mounting regions 22CM that are interconnected by
flexible interconnect paths (sometimes referred to as branches,
arms, elongated segments, interconnects, etc.) such as flexible
interconnect paths 22I. Signal routing lines 32 may be formed from
metal traces in component mounting regions 22CM and interconnect
paths 22I. Interconnect paths 22I may have serpentine shapes or
other suitable elongated shapes (e.g., meandering elongated shapes,
etc.) to promote stretching and bending without damaging signal
routing lines 32. Components 24 may be soldered to signal path
solder pads formed from metal traces in component mounting regions
22CM or may be coupled to signal lines 32 using other suitable
conductive connections (e.g., conductive connections formed from
welds, conductive adhesive, etc.). Component mounting regions 22CM
may be rectangular, circular, oval, may have shapes with
combinations of curved and straight edges, or may have other
suitable shapes.
Flexible circuit substrate 22 may be formed from a flexible polymer
such as polyimide or other flexible dielectric. Substrate 22 may,
for example, include one or more, two or more, or three or more
sheets of laminated polyimide (as examples). Metal traces may be
formed on one or both sides of substrate 22 and/or may be embedded
between polyimide sublayers in substrate layer 22.
Component mounting regions 22CM may be arranged in a line (e.g., to
form a one-dimensional array), may be tiled in two dimensions
(e.g., to form a two-dimensional array having rows and columns),
and/or may be organized in other suitable patterns. Light-emitting
diodes 26 and other electrical devices associated with electrical
components 24 may be used to create components 16 that serve as
status indicator lights, displays that display images for a user,
and/or other components 16. Components 24 that include sensors
(e.g., capacitive touch sensing circuitry, force sensors,
light-based touch sensors, etc.) can be formed in one-dimensional
arrays (e.g., to serve as buttons or one-dimensional touch
sensitive input devices) or may be formed in two-dimensional arrays
(e.g., to form two-dimensional touch sensors). If desired, a
two-dimensional mesh-shaped configuration may be used for substrate
22, components 24 may be mounted on a two-dimensional array of
regions 22CM, and component 16 may form a two-dimensional touch
sensitive display (as an example). Haptic devices may be
incorporated into electrical components 24 to provide component 16
with haptic output capabilities.
Whether arranged to form a one-dimensional or two-dimensional array
or other suitable flexible circuit configuration, flexible circuit
substrate 22 may be delicate due to the presence of thin elongated
structures such as interconnect paths 22I. To ensure that flexible
circuit substrate 22 is sufficiently robust to withstand handling
during assembly such as when being attached to support structure 12
of item 10 (FIG. 1), flexible circuit substrate 22 may be provided
with temporary support structures such as breakable tethers 34 of
FIG. 3. Tethers 34 may be formed from the same material as
substrate 22 (e.g., polyimide) or may be formed from a different
material (e.g., an organic or inorganic material that is coupled
between opposing portions of substrate 22). Substrate 22 may be
patterned using laser cutting, die cutting, etching, photoimaging
(e.g., using a mask to expose and develop a photoimageable to form
polymer substrate 22), printing and/or other suitable patterning
techniques. During patterning, tethers 34 may be left in place in
substrate 22 at locations that bridge gaps 36 between component
mounting regions 22CM and interconnect paths 22I or at other
suitable locations that help provide temporary support to substrate
22 (e.g., temporary coupling between component mounting regions
22M). Once component 16 has been mounted in structure 12, component
16 may be flexed or otherwise manipulated to break tethers 34 and
thereby release serpentine interconnect paths 22I. This ensures
that flexible circuit substrate 22 and component 16 will achieve
its desired maximum flexibility during normal use of item 10.
If desired, tethers 34 may have narrowed portions 34' or other
selectively weakened portions. Narrowed portions 34' serve as
stress concentrators that ensure that tethers 34 break in a
controllable fashion at known locations during manufacturing.
Tethers 34 may all have the same strength or different tethers
within the set of tethers coupling together adjacent pairs of
component mounting regions 22CM may have different strengths.
Tethers of different strengths can be broken by applying
progressively increasing amounts of force. In the example of FIG.
3, the widths of narrowed portions 34' increase progressively for
tethers 34-1, 34-2, and 34-3. With this arrangement, tether 34-1
breaks relatively easily, tether 34-2 breaks with more difficulty
than tether 34-2 and therefore breaks only after more force is
applied than was applied to break tether 34-1, and tether 34-3
breaks when even more force is applied than was used to break
tether 34-2. Different amounts of breaking force may be applied at
different manufacturing stages so that component 16 has different
amounts of flexibility at different stages.
In the illustrative configuration of FIG. 3, tethers 34 have a
bowtie shape with a narrowed central portion 34'. FIG. 4 shows how
tether 34 may be narrowed from one side. Tether 34 of FIG. 5 has an
edge with curved portions. FIG. 6 shows how tether 34 may have a
sawtooth shape. In the example of FIG. 7, tether 34 has rectangular
slot 38 that facilitates breakage. In the example of FIG. 8, tether
34 has an oval or teardrop shaped opening 40 that facilitates
breakage. Tether 34 of FIG. 9 is selectively weakened by the
presence of comb-shaped narrowing edge recesses 42. FIG. 10 shows
how tether 34 may be narrowed using rectangular notches. Tether 34
of FIG. 11 has pointed notches.
As shown in FIG. 12, tethers 34 may be formed from material that is
separate from the material of flexible circuit substrate 22.
Tethers 34 may, in general, be formed from plastic, metal, ceramic,
printed material, material attached to substrate 22 by adhesive or
other attachment mechanisms, or other suitable materials. If
desired, tethers 34 may extend outwardly from component mounting
regions 22CM, as shown in FIG. 13. The configurations of FIGS. 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, and 13 are merely illustrative. In
general, tethers 34 may have any suitable shapes or sizes and may
be formed from integral portions of substrate 22 and/or one or more
additional materials. Tethers 34 serve as temporary attachment
structures that help hold component mounting regions 22CM together
during assembly so that interconnect paths 22I are not damaged and
may therefore sometimes be referred to as being sacrificial,
breakable, temporary, etc.
FIG. 14 shows how item 10 may be stretchable. In the example of
FIG. 14, structure 12 of item 10 is being stretched around a
cylindrical object 40 in directions 42. Object 40 may be, for
example, a wrist of a person, may be another human body part, may
be an inanimate object, or may be any other suitable structure. In
configurations such as those in which components 24 contain
light-emitting diodes in a two-dimensional array to form a display
that displays images for a user, distortion of displayed images may
be undesirable. To prevent flexible circuit substrate 22 of item 10
from deforming in a way that distorts displayed images as item 10
is stretched along a first dimension (parallel to directions 42)
flexible circuit substrate 22 (and, if desired, structure 12) may
contain structures that expand outwardly in a perpendicular second
dimension (parallel to directions 44) as flexible circuit substrate
22 is stretched in directions 42. Because circuit substrate 22
stretches outwardly in directions 44 as structure 12 and circuit
substrate 22 are stretched in directions 42, substrate 22 and the
components 24 on substrate 22 will expend outwardly by equal
amounts. The pitch (center-to-center spacing) of components 24 may
increase, but pitch expansion will occur equally in the dimension
parallel to directions 42 and in the orthogonal dimension parallel
to directions 44 so the array of components 24 on substrate 22 will
not become distorted and will not produce distorted images.
Materials that exhibit equal expansion in orthogonal directions
when stretched (e.g., structures that become thicker/wider
perpendicular to applied force when stretched) are characterized by
a negative Poisson's ratio and may sometimes be referred to as
auxetics. Distortion of the array of components 24 in component 16
can therefore be minimized by forming component 16 from an auxetic
flexible circuit substrate. In general, substrate 22 may be
provided with any suitable patterns of component mounting regions
and interconnect paths 22I that form an auxetic flexible circuit
substrate. For example, substrate 22 may be formed from an auxetic
mesh-shaped patterned polyimide layer or other substrate shape in
which paths 22I help laterally press apart substrate 22 when
stretched.
FIGS. 15 and 16 are top views of an illustrative flexible circuit
substrate 22 that has an auxetic configuration. Initially,
substrate 22 may have an unexpanded configuration of the type shown
in FIG. 15. When substrate 22 of FIG. 15 is stretched outwardly in
directions 42, each component mounting region 22CM will rotate, as
shown by arrows 46 of FIG. 15. This causes elongated interconnect
paths 22I to move into the configuration of FIG. 16 so that
component mounting regions 22CM and components 24 on regions 22CM
are moved outwardly in direction 44 and so that substrate 22
expands equally in both directions 42 and directions 44.
Interconnect paths 22I may be elongated straight segments (as shown
in FIG. 16) or may have elongated serpentine shapes as shown in
FIG. 2. Substrates such as substrates 22 of FIGS. 15 and 16 may
sometimes be referred to as auxetic mesh substrates because
interconnect paths 22I form a two-dimensional lattice
interconnecting a two-dimensional array of component mounting
regions 22CM and components 24.
Additional illustrative mesh-shaped flexible circuit substrates 22
for component 16 are shown in FIGS. 17, 18, and 19. As shown in
FIGS. 17, 18, and 19, substrate 22 may have various different
auxetic mesh patterns that expand equally in directions 44 and 42
when stretched in direction 42. The flexible circuit substrate may,
if desired, include optional non-auxetic portions 22NA (i.e.,
flexible substrate regions with positive Poisson's ratio) formed
from serpentine interconnect paths 22I' or other suitable substrate
material. As shown in FIGS. 17, 18, and 19, temporary tethers 34
may, if desired, be used in holding paths 22I and/or 22I' of the
flexible circuit substrates of FIGS. 17, 18, and 19 together as
components 16 are assembled with structures 12 to form item 10.
The foregoing is merely illustrative and various modifications can
be made to the described embodiments. The foregoing embodiments may
be implemented individually or in any combination.
* * * * *